1. Field of the Invention
The present invention relates to storage apparatus and a storage system.
2. Description of the Related Art
For example, due to the large volumes of various types of data that they handle, government organizations, private companies, educational institutions and the like utilize relatively large-scale storage systems to manage data. These storage systems are constituted comprising, for example, disk arrays and other such storage apparatus. For example, a storage apparatus is constituted by arranging a large number of storage devices in an array, and providing a storage area based on RAID (Redundant Array of Inexpensive Disks). At least one logical volume is formed on a physical storage area provided by a group of storage devices, and this logical volume is provided to a host computer (hereinafter referred to simply as “host”). A host can write and read data to and from a logical volume by sending a write command or a read command.
The data that companies and the like must manage is increasingly daily. For this reason, companies, for example, are expanding storage systems by deploying new storage apparatus in the storage systems. Two methods for introducing new-model storage apparatus into a storage system can be cited. One is a method whereby an old-model storage apparatus are replaced with a new-model storage apparatus (Domestic Announcement 10-508967). The other one is a method whereby the old-model storage apparatus are used in combination with new-model storage apparatus.
However, when converting completely from an old-model storage apparatus to a new-model storage apparatus, it is not possible to put the old-model storage apparatus to practical use. By contrast, when an attempt is made to use the old-model storage apparatus in combination with new-model storage apparatus, the constitution of the storage system is made more complex, requiring greater time and effort to manage and operate the system.
Accordingly, technology constituted such that a host is connected to a first storage apparatus, and, in addition, the first storage apparatus is also connected to a second storage apparatus, and the first storage apparatus processes access requests from the host by proxy, is also well known (Japanese Patent Laid-open No. 2004-005370). In this technology, the first storage apparatus also receives and processes commands destined for the second storage apparatus. When necessary, the first storage apparatus issues a command to the second storage apparatus, receives those processing results, and transmits them to the host.
The storage resources of an old model storage apparatus can be effectively utilized by connecting a first storage apparatus and a second storage apparatus in series such that the first storage apparatus receives access requests from a host as disclosed in the above-mentioned literature.
However, in recent years, consideration has also been given to constructing wider area storage networks by interlinking a plurality of sub-networks comprising various storage apparatus. In a wide area storage system such as this, a large number of diverse types of storage apparatus are readily intermixed, forming what is called a heterogeneous storage environment. Under a heterogeneous storage environment, the management and operation of the respective storage apparatus takes time and effort.